In some high-speed and high-precision signal processing and conversion circuits, processes of sampling and transmission of an analog signal are generally required to be implemented by some switches. Signals that control the switches being turned on and off are generally a set of clock signals. On the premise that characteristics of transistors constructing the switches are unchanged, the higher a high-level voltage of a control signal is, the smaller an on-resistance of each of the switches is, so that a speed at which the analog signal passes through the switches is increased and distortion of the analog signal is reduced.
Currently, a voltage of a switch control signal generated by a clock voltage step-up circuit is generally related to a voltage of a signal to be sampled. When used in some situations that a voltage range of the signal to be sampled is large, the clock voltage step-up circuit may result in some reliability problems due to the voltage of the control signal being too high. Thus, there is a need for a clock voltage step-up circuit to limit step-up amplitude of the voltage of the switch control signal to a safe range to prevent possible reliability problems.